<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin:0;
            padding: 0;
        }
        .container{
            /* display: flex; */
        }
        .aside,.main{
            height:500px;
        }
        .aside {
            width:300px;
            background-color: green;
            /* display: inline-block; */
            float:left;
        }
        .main {
            /* flex:1; */
            background-color: red;
            overflow: hidden;
            /* display: inline-block; */
            /* margin-left:300px; */
            /* float:left;
            width:calc(100% - 300px); */
        }
    </style>
</head>
<body>
    <!-- 自适应的两列式布局  
        设置一套布局，两列布局  aside 300px  剩下的交给main 
        左右
        侧栏固定宽度，主栏宽度自适应
    -->
    <div class="container">
        <div class="aside"></div>
        <div class="main"></div>
    </div>
</body>
</html>